Quartz – At in the heart of Silicon Valley filled up their tanks with a heavy metal most Americans assumed was banished long ago: lead. Reid-Hillview was not unusual in this respect. Virtually every small airplane in the US burns fuel containing tetraethyl lead (TEL), an additive introduced in the 1920s to boost octane levels. It’s so toxic, a splash on the skin can be lethal. But in January, Santa Clara County, which owns Reid-Hillview, imposed the first ban in the US on refueling with leaded aviation gas, sparking a fight with the Federal Aviation Administration (FAA) and forcing some plane owners to refuel their airplanes elsewhere. County officials have since reaffirmed the ban, and now other airports are considering following suit. Prompted by scientific research showing higher than average lead levels in children living near Reid-Hillview, Quartz has done the first investigation combining lead emissions data at the country’s top civil aviation airports with flight paths for small, piston-engine aircraft over affected neighborhoods. The analysis of over 350 million aircraft locations from planes taking off and landing in the US shows the extent to which lead-fuel burning aircraft regularly expose homes, parks, schools, and playgrounds across the country. The US Environmental Protection Agency (EPA) estimates 16 million people—and 3 million children—live within a kilometer of these airports…”